How to save and use the Client in AppState?

[InShade]

How can I reuse the client, i.e. reuse the underlying connection
in function create_user?

Trying to save the Client in AppState and use it so I don't have to create it again each time.

It doesn't work in my function. Want without sqlx.

How to do it correctly?
Please, fix my code.
`

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {

   // POSTGRESQL - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
   let (client, connection) = tokio_postgres::connect("host=localhost ***", NoTls).await?;
   tokio::spawn(async move {
    if let Err(e) = connection.await {
       eprintln!("connection error: {}", e);
    }
   });
   //
   let state = AppState {
      d: Arc::new(Mutex::new(vec![])),
      client: client
   };
   //
   // works without sqlx:
   let row = &client.query("insert into test (inf, res) values ($1,$2)", &[&"txt", &100]).await?;
   // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 

   // AXUM  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
   // ...
   let app = Router::new()
    .route("/info", post(create_user))
    .with_state(state);

   let listener = tokio::net::TcpListener::bind("127.0.0.1:3000").await.unwrap();
   axum::serve(listener, app).await.unwrap();
   // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
   // ...   
Ok(())
}


async fn create_user(

    State(state): State<AppState>,
    Json(json): Json<Value>,
 ) -> Json<Value> {

    let mut s: String = "".to_string();
    // ...

    // Trying to save the Client in AppState and use it so I don't have to create it again each time.
    // doesn't work. want without sqlx :

    let row = &client.query("insert into test (inf, res) values ($1,$2)", &[&"abc", &10]).await.unwrap();

    // ...
    // println!("s = {:?}", &s);
    Json(serde_json::from_str::<serde_json::Value>(&s).expect("REASON"))
}


#[derive(Debug, Clone)]
struct AppState {
    d: Arc<Mutex<Vec<String>>>,  // вектор строк 
   // client: reqwest::Client,
   client: tokio_postgres::Client,
}

`

[mladedav]

You didn't provide any error messages or what specifically you have issues with so there isn't much help we can provide.

[yanns]

What is the issue if you save your client in AppState?

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {

   // POSTGRESQL - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
   let (client, connection) = tokio_postgres::connect("host=localhost ***", NoTls).await?;
   tokio::spawn(async move {
    if let Err(e) = connection.await {
       eprintln!("connection error: {}", e);
    }
   });

   // creates the client
   let created_client = &client.query("insert into test (inf, res) values ($1,$2)", &[&"txt", &100]).await?;

   //
   let state = AppState {
      d: Arc::new(Mutex::new(vec![])),
      client: client,
      created_client: created_client, // or Arc::new(created_client)
   };
   //
   // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 

   // AXUM  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
   // ...
   let app = Router::new()
    .route("/info", post(create_user))
    .with_state(state);

   let listener = tokio::net::TcpListener::bind("127.0.0.1:3000").await.unwrap();
   axum::serve(listener, app).await.unwrap();
   // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
   // ...   
Ok(())
}


async fn create_user(

    State(state): State<AppState>,
    Json(json): Json<Value>,
 ) -> Json<Value> {

    let mut s: String = "".to_string();
    // ...


    let row = state.created_client;

    // ...
    // println!("s = {:?}", &s);
    Json(serde_json::from_str::<serde_json::Value>(&s).expect("REASON"))
}


#[derive(Debug, Clone)]
struct AppState {
    d: Arc<Mutex<Vec<String>>>,  // вектор строк 
   // client: reqwest::Client,
   client: tokio_postgres::Client,
   created_client: <type of your created client>
}

[yanns]

What is the issue if you save your client in AppState?

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {

   // POSTGRESQL - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
   let (client, connection) = tokio_postgres::connect("host=localhost ***", NoTls).await?;
   tokio::spawn(async move {
    if let Err(e) = connection.await {
       eprintln!("connection error: {}", e);
    }
   });

   // creates the client
   let created_client = &client.query("insert into test (inf, res) values ($1,$2)", &[&"txt", &100]).await?;

   //
   let state = AppState {
      d: Arc::new(Mutex::new(vec![])),
      client: client,
      created_client: created_client, // or Arc::new(created_client)
   };
   //
   // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 

   // AXUM  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
   // ...
   let app = Router::new()
    .route("/info", post(create_user))
    .with_state(state);

   let listener = tokio::net::TcpListener::bind("127.0.0.1:3000").await.unwrap();
   axum::serve(listener, app).await.unwrap();
   // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
   // ...   
Ok(())
}


async fn create_user(

    State(state): State<AppState>,
    Json(json): Json<Value>,
 ) -> Json<Value> {

    let mut s: String = "".to_string();
    // ...


    let row = state.created_client;

    // ...
    // println!("s = {:?}", &s);
    Json(serde_json::from_str::<serde_json::Value>(&s).expect("REASON"))
}


#[derive(Debug, Clone)]
struct AppState {
    d: Arc<Mutex<Vec<String>>>,  // вектор строк 
   // client: reqwest::Client,
   client: tokio_postgres::Client,
   created_client: <type of your created client>
}

[InShade]

@yanns

did not give any result,
it was suggested to do it like this (error[E0106]: missing lifetime specifier):

then like this (error[E0782]: trait objects must include the dyn keyword):
State(state): dyn for<'a> State<AppState<'a>>,

now the only mistake (error[E0404]: expected trait, found struct State):

[yanns]

Your AppState should have any lifetime.
Try this:

    #[derive(Debug, Clone)]
    struct AppState {
       //pool: PgPool,
       created_client: Vec<Row>,  // or Arc<Vec<Row>> 
    }

[InShade]

@yanns

    let state = AppState {
        // ...
        created_client: created_client.to_vec(),        //      or Arc::new(created_client)
                                       ^^^^^^^^_  without  `.to_vec()`  was forced to install with <'a>
    };

Thanks, the code variant

async fn create_user(

   State(state): State<AppState>,
   Json(json): Json<Value>,
) -> Json<Value> {

    // let row = &client.query("insert into test (inf, res) values ($1,$2)", &[&"abc", &10]).await.unwrap();
    // let row = state.created_client;
    state.created_client = &client.query("insert into ... ").await.unwrap();
                            ^^^^^^___  error: not found in this scope    
    // ...
}

When

#[derive(Debug, Clone)]
struct AppState {
   // client: Client,
   // created_client: Vec<Row>,         // or Arc<Vec<Row>>
    client: tokio_postgres::Client,     // error[E0277]: the trait `Clone` is not implemented for `tokio_postgres::Client`
    created_client: Vec<tokio_postgres::row::Row>,
}

let state = AppState {
   // ...
   client: client,
   created_client: created_client.to_vec()
};

gives an error:

error[E0277]: the trait Clone is not implemented for tokio_postgres::Client

[yanns]

yes, you can try to put it into an Arc.

[InShade]

Thank you!